JPH0946031A - Structure of conductor connecting edge of flexible printed board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent defective brazing and to enhance connecting strength by eliminating scattering of solder when the edges of a plurality of conductors formed on a flexible printed board are connected to a plural of terminal parts of electronic components and an ink-jet recorder by brazing. SOLUTION: A plurality of conductors are formed on a base film 21 at a minute pitch. The edges of a plurality of the conductors are connected to a plurality of terminal parts 16a of a recording head 14 of an ink-jet recorder by soldering, respectively. In this structure, slits 22b are formed at the edges of a plurality of the conductors. Thus, the fused solder is stored in the slits 22b, the connecting strength is increased by fillets F formed on both sides of the slits, the gas generated in soldering is discharged from the opening ends of the slits and the defective brazing caused by the gas pressure is eliminated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an end structure for connecting a flexible printed circuit board, and in particular, a plurality of conductive wires formed on a base film are brazed to a plurality of terminal parts of an electronic component or an ink jet recording apparatus. The present invention relates to a device capable of preventing defective brazing when connecting and enhancing the connection strength.

[0002]

2. Description of the Related Art Conventionally, in an ink jet recording apparatus for recording characters or images on recording paper by ejecting ink from a plurality of ejection nozzles provided in a recording head, a head holder is mounted on a carriage movable in a recording direction. The head holder is provided with an ink ejecting mechanism including a recording head facing the recording paper, and a cylindrical connecting cylinder (so-called manifold) forming an ink supply path communicating with the recording head. Further, an ink cartridge for accommodating the ink to be supplied to the recording head and having an ink supply port fitted to the connecting cylinder portion is detachably mounted.

For example, in Japanese Unexamined Patent Publication No. 4-182138, a plurality of ink supply passages are formed, and an ink supply pipe for supplying ink to each ink supply passage is formed, and a piezoelectric element is provided in each ink supply passage. An ink jet recording head of an ink jet recording device is provided with a central piezoelectric substrate on which a conductive wire made of a copper wire is formed, and a base of a flexible printed circuit board is provided at a terminal portion of a plurality of conductive wires formed on the central piezoelectric substrate. By brazing the ends of a plurality of conducting wires formed on the film, for example, by connecting by soldering, by deforming the piezoelectric element based on a plurality of drive signals supplied through the flexible printed board , A recording head for ink jet which ejects ink to record an image.

By the way, when connecting ends of a plurality of conductive wires of a flexible printed circuit board to terminals of a plurality of conductive wires of a central piezoelectric substrate provided in a recording head by soldering, as shown in FIG. In order to reduce the size of the recording head, the line widths of the plurality of conductor wire end portions 122a and the pitches between the conductor wires are as small as 0.5 mm or less. Therefore, the electrolytic plating solder 130 is applied to the plurality of conductor wire end portions 122a. Is applied thinly, and a flux (so-called tar or rosin) that promotes soldering is applied in advance, and the flexible printed board 120 is applied to the terminal portion 1 of the lead wire of the central piezoelectric substrate 114.
The plurality of conductor end portions 122a are soldered all at once by positioning them on the 16a and applying pressure while heating at a predetermined temperature.

[0005]

As described above, when the ends of the conductors formed on the flexible printed board are connected to the terminals of the plurality of conductors of the central piezoelectric substrate by soldering, as shown in FIG. The electrolytic plating solder 130 applied to the conductive wire end portion 122a of the flexible printed circuit board 120 is melted, and the flux is further melted. Here, since the flux is a mixture of "alcohol" and "alcohol", when the flux is heated to a high temperature (for example, about 300 ° C), gas is generated from the "tar" and "Alcohol" evaporates explosively in a moment.

By the way, since the thickness of each conducting wire is as thin as about 18 to 35 μm and the pitch between conducting wires is as small as about 0.5 mm, two conducting wires in which these conducting wire end portions 122a and terminal portions 116a are overlapped with each other are provided. Since the joint space S surrounded by the joint and the two base films 121 and 115 is very small, the gas generated when the “alcohol” evaporates and the gas generated from the “tar” is in the atmosphere. It cannot be escaped inside and is confined in the minute joint space S, the gas pressure becomes high, and the plating solder 13
0 boils. At this time, the boiled liquid plating solder 130 scatters at a stretch and is formed as a so-called solder bridge 130a across the two conductor joints, or scatters as a plurality of solder balls 130b. That is, the formed solder bridge 130a causes the two conductor end portions 122a to be short-circuited, or the solder balls 130b gradually corrode by containing moisture, which causes migration between the two conductors. However, there is a problem such as deterioration of the insulation property of.

An object of the present invention is to eliminate wax scattering when connecting ends of a plurality of conducting wires formed on a flexible printed circuit board to a plurality of terminals of an electronic component or an ink jet recording apparatus by brazing. It is an object of the present invention to provide an end portion structure for connecting a conductor of a flexible printed circuit board, which can prevent defective attachment and enhance connection strength.

[0008]

According to another aspect of the present invention, there is provided a conductor connecting end structure for a flexible printed circuit board, wherein a plurality of conductors are formed on a base film at a fine pitch, and the ends of the plurality of conductors are electronic parts. Is a conductor-connecting end structure of a flexible printed circuit board that is respectively connected to the ends of a plurality of conductors by brazing, wherein the ends of the plurality of conductors are made of a conductor for accumulating molten solder during brazing. Each of the slits is formed at the central portion in the width direction.

To explain the operation, the ends of the plurality of conductors formed on the base film of the flexible printed circuit board are often connected by brazing, particularly by soft brazing, and the ends of the plurality of conductors are often connected. Since the brazing is applied together with the flux, the brazing and the flux are simultaneously heated during brazing. At this time, of the melted brazing filler metal, excess brazing filler metal other than the brazing filler metal that adheres to the joint surface at the end of the conducting wire flows into the slit formed in the conducting wire and collects to form a fillet. As a result, gas is generated from the heated flux and is confined between the end portions of the conductor wire, and even if the gas pressure becomes high, there is almost no braze scattered outside the conductor wire end portion, When the ends of the conductors formed on the flexible printed circuit board are connected to the ends of multiple conductors of an electronic component by brazing, brazing defects can be prevented and the fillets formed on both sides of the slit increase the connection strength. Can be increased.

According to another aspect of the present invention, there is provided a flexible printed circuit board end portion structure for connecting conductive wires, wherein a plurality of conductive wires are formed on a base film at a fine pitch, and the end portions of the plurality of conductive wires form a plurality of recording heads of an ink jet recording apparatus. A conductor connecting end structure of a flexible printed circuit board that is respectively connected to the ends of the conductors by brazing, wherein the width direction of the conductors for accumulating molten brazing at the ends of the plurality of conductors The slits located at the center are formed respectively.

Explaining the operation, the same operation as in claim 1 is performed, and excess brazing filler metal melted by heating flows into the slit formed in the conductive wire and collects to form a fillet. As a result, gas is generated from the heated flux and is confined between the end portions of the conductor wire, and even if the gas pressure becomes high, there is almost no braze scattered outside the conductor wire end portion, When the ends of the conductors formed on the flexible printed circuit board are connected to the ends of multiple conductors of the inkjet recording device by brazing, it is possible to prevent brazing defects, and the fillets formed on both sides of the slits provide connection strength. Can be increased.

According to a third aspect of the invention, there is provided an end portion structure for connecting a conductor of a flexible printed circuit board according to the first or second aspect of the present invention, wherein each slit has a length of a portion to be brazed at an end portion of the conductor. They are formed to be substantially equal. Explaining the operation, the same operation as in claim 1 or claim 2 is achieved, but the slits for accommodating the brazing wire are formed to have substantially the same length as the brazed portion of the end portion of the conductor wire. As a result, it is possible to sufficiently exert the brazing effect of accumulating the extra brazing material, and it is possible to reliably prevent the scattering of the brazing material.

According to a fourth aspect of the present invention, there is provided an end portion structure for connecting a conductor wire of a flexible printed circuit board, wherein each of the slits is formed in an open shape at an end portion of the conductor wire. Explaining the operation, the same operation as in claim 3 is achieved, but since each slit for accommodating the brazing wire is formed in an open shape at the end of the conductor wire, it is generated from flux or the like when brazing. Since the gas escapes from the open slit, it is possible to perform degassing when brazing, and it is possible to more reliably prevent the wax from scattering.

[0014]

Embodiments of the present invention will be described below with reference to the drawings. The present embodiment is provided with an ink jet recording apparatus (not shown), and a conductor connecting end portion of a flexible printed circuit board connected to a plurality of terminal portions of a recording head unit that ejects recording ink contained in an ink cartridge. This is a case where the present invention is applied to a structure. First, a recording head unit (corresponding to a recording head of an ink jet recording apparatus) 10 will be described. As shown in FIG. 1, basically, a plurality of (eg, 64) head end portions of a plate-shaped head main body 11 are provided. ), The ink jet nozzles 12 are formed in one row, and the connecting cylinder portion 13 is formed in a protruding shape on the head main body portion 11. Further, a thin plate thickness is formed on the rear end portion of the head main body portion 11. The connecting portion 14 is formed.

The connecting cylinder portion 13 is inserted into an ink supply port formed in an ink cartridge (not shown) and is brought into contact with an ink absorber housed in the ink cartridge and absorbing and holding recording ink. By doing so, the ink is supplied to the ink ejecting nozzle 12, and the ink supplied to the connecting cylinder portion 13 is supplied to a plurality of inks via an ink passage (not shown) formed in the connecting cylinder portion 13. It is branched into a passage (not shown) and is supplied to the ink ejection nozzle 12 through each ink supply passage.

Further, a vibration plate composed of a piezoelectric element (not shown) is provided in the middle of each ink supply passage, and a plurality of conducting wires 16 for supplying a drive signal to each piezoelectric element are arranged on the base film 15 at a minute pitch. The plurality of conducting wires 16 are extended to the connecting portion 14 in a substantially parallel shape. That is, each of the terminal portions 16a of the plurality of conducting wires 16 provided in the connecting portion 14 is in an exposed state, and each terminal portion 16a
When a drive signal is supplied to the recording medium, the piezoelectric element to which the drive signal is supplied is deformed, so that the minute ink in the ink supply passage is ejected from the ink ejection nozzles 12 onto the recording sheet to form an image. .

Next, the conductor connecting end structure of the flexible printed board 20 connected to the terminal portions 16a of the plurality of conductors 16 formed in the connecting portion 14 will be described with reference to FIGS. First, the flexible printed circuit board 20 has flexibility with excellent heat resistance and insulation properties, for example, on a base film 21 made of a polyimide resin,
The plurality of conductive wires 22 made of copper are arranged at a fine pitch (for example, about
The cover wire 23 is made of, for example, a polyimide resin, and protects the plurality of conductive wires 22 in the same manner as the base film 21.

Next, the structure of the end portion for connecting the conductor will be described. At the end portion of the flexible printed circuit board 20,
The cover film 23 is cut off by a predetermined distance, and the plurality of conductor wire end portions 22a are exposed. Here, each conductor 22 has a line width of about 0.25 mm and a thickness of about 18 to 35 μm, and the plurality of conductors 22 have a fine pitch (for example, about 0.5 mm).
It is formed with.

By the way, as shown in FIG. 3, among the end portions of the base film 21, between the end portions of the plurality of conductive wire end portions 22a, slits for degassing when brazing, for example, soldering are performed. 21a are formed to have substantially the same length as the soldered portion of the conductor wire end 22a. Further, a slit 22b, which is located in the widthwise central portion of the conductor wire end portion 22a for accumulating molten solder at the time of soldering, is formed on the plurality of conductor wire conductor end portions 22a. Are formed almost equally.
Further, each slit 22b is formed in an open shape at the tip of the conductor wire end 22a. These slits 21
The a and 22b may be formed by etching or laser light.

Next, the operation of soldering the plurality of conductor wire end portions 22a formed on the flexible printed circuit board 20 to the terminal portions 16a of the plurality of conductor wires formed on the connecting portion 14 of the head body 11 will be described. . At the time of soldering, first, electrolytic plating solder 30 is thinly applied to the plurality of conductor wire end portions 22a, and flux (so-called resin or rosin) that promotes soldering is applied to the flexible printed circuit board as shown in FIG. 20 is turned upside down so that the end portions 22a of the plurality of conductors face downward, and the terminals 20 are aligned and placed on the terminal portions 16a of the plurality of conductor wires 16 formed in the connecting portion 14 of the head body 11. Then, while heating a heating plate (not shown) at a predetermined temperature (for example, about 300 ° C.), the base film 21 at the end portion of the flexible printed circuit board 20 is pressed from above so that the plurality of conductive wire end portions 22a are removed. It can be soldered all at once.

At this time, as shown in FIG. 4, the heat heated through the base film 21 is transferred to the plating solder 30 through the lead wire end 22a, and the plating solder 30 is heated and melted, and the flux Are also heated at the same time. Here, since the flux is a mixture of "alcohol" and "alcohol", when the flux is heated to a high temperature (for example, about 300 ° C), gas is generated from the "tar" and "Alcohol" evaporates explosively in a moment.

By the way, the thickness of the conductor wire end portion 22a is about 18 to
Since it is as thin as 35 μm and the pitch between conductors is as small as about 0.5 mm, it is surrounded by two conductor joints where the conductor end 22a and the terminal 16a are superposed and two base films 15 and 21. Although the joint space S is very small, the gas generated when “alcohol” explosively evaporates and the gas generated from the “tar” passes through the minute joint space S through the slit 21a and is immediately released into the atmosphere. At the same time as it efficiently escapes into the interior, it also escapes into the atmosphere from the tip of the slit 22b.

That is, all the gas generated during soldering is efficiently and easily released into the atmosphere through each slit 22b, and the plating solder 30 melted in a boiling state by heating is mainly At the same time as it flows into the slit 22b, it is squeezed out to the outside of the conductor wire end 22a, though a small amount, and fillets F are formed at a plurality of locations. As a result, the connection strength by soldering is improved by the plurality of fillets F including the fillets F formed on both sides of the slit 22b, and the plating solder 30 can be prevented from scattering to prevent defective soldering. Since no solder balls are formed, it is possible to surely enhance the insulating property between these conducting wires.

Thus, since the slits 22b for accumulating the plated solder 30 melted at the time of soldering are formed at the plurality of conductor wire end portions 22a, respectively, each having a length substantially equal to the length of the portion to be soldered, the conductor wires are formed. Excess solder other than the solder that adheres to the joint surface of the end portion flows into the slit 22b formed in the end portion 22a of the conductive wire and collects as a fillet F. Even if a gas is generated during soldering, the plating solder will scatter. Since 30 is almost not present outside the conductor wire end portion 22a, the conductor wire end portion 22a of the flexible printed circuit board 20 is connected to the terminal portions 16a of the plurality of conductor wires 16 formed in the connecting portion 14 of the head body 11 by soldering. It is possible to prevent defective soldering and to improve the connection strength by the fillets F formed on both sides of the slit 22b. It is possible to increase.

When the conductors 22 formed on the base film 21 of the flexible printed circuit board 20 have a large line width or a large pitch such as 1.5 to 2.0 mm, the slits 22b for accumulating the molten solder are formed. It is obvious to an existing technology or a person skilled in the art regarding the above-described embodiment that two or three rows are provided, or the slit 21a for degassing is not provided, or a slit is formed on the terminal portion side of the recording head. Various modifications may be made based on the above technology. Further, it goes without saying that the present invention can also be applied to the conductor wire connection end structure of various flexible printed boards that are connected to a plurality of terminal portions of an electronic component by various kinds of brazing other than soldering.

[0026]

According to the conductor connecting end structure of the flexible printed circuit board according to the first aspect of the present invention, the slits for accumulating the molten solder during brazing are formed at the ends of the plurality of conductors. Excess braze other than the wax that adheres to the joint surface at the end of the conductor flows into the slit formed in the conductor and collects as a fillet. Even if gas is generated during brazing, the braze will scatter even if gas is generated. Since there is almost no outside, it is possible to prevent brazing defects when connecting the ends of the conductors formed on the flexible printed circuit board to the ends of multiple conductors of the electronic component by brazing, The formed fillet can increase the connection strength.

According to the conductor wire connection end structure of the flexible printed circuit board of the second aspect, as in the first aspect, the excess brazing material melted by heating flows into the slit formed in the conductor wire and accumulates to form a fillet. Since there is almost no scattered solder outside the end of the conductive wire, when the end of the conductive wire formed on the flexible printed circuit board is connected to the ends of a plurality of conductive wires of the inkjet recording device by brazing, the solder will not be soldered. It is possible to prevent improper attachment and increase the connection strength by the fillets formed on both sides of the slit.

According to the conductor connecting end structure of the flexible printed circuit board of the third aspect, the first or second aspect is provided.
The same effect as in, but each slit for holding the brazing wire is formed to be approximately equal to the length of the part to be brazed at the end of the conductor wire, so a sufficient brazing effect for accumulating excess brazing material It can be demonstrated, and it is possible to reliably prevent wax from scattering.

According to the conductor connecting end structure of the flexible printed circuit board of the fourth aspect, the same effect as in the third aspect can be obtained, but each slit for accommodating the brazing wire is opened at the end of the conductor. Since it is formed, the gas generated from flux etc. escapes from this open slit when brazing, so it is possible to degas when brazing, and to prevent brazing from scattering. be able to.

[Brief description of drawings]

FIG. 1 is a schematic perspective view of a recording head unit according to an embodiment of the invention.

FIG. 2 is a partial perspective view showing an end portion of a flexible printed board.

FIG. 3 is a partially enlarged perspective view of a flexible printed circuit board.

FIG. 4 is a vertical sectional front view taken along the line AA of FIG.

FIG. 5 is a view corresponding to FIG. 4 according to a conventional technique.

[Explanation of symbols]

 10 recording head unit 16 conducting wire 16a terminal portion 20 flexible printed circuit board 21 base film 22b slit

Claims (4)

[Claims] 1. A conductor connection of a flexible printed circuit board, wherein a plurality of conductors are formed on a base film at a fine pitch, and ends of the conductors are connected to ends of the conductors of an electronic component by brazing. A flexible printed circuit board, which is an end structure for use, wherein slits are formed at ends of the plurality of conductive wires, respectively, which are located at a central portion in a width direction of the conductive wires for accumulating molten brazing during brazing. End structure for connecting conductors. 2. A flexible print in which a plurality of conducting wires are formed on a base film at a fine pitch, and ends of the plurality of conducting wires are respectively connected to ends of a plurality of conducting wires of a recording head of an ink jet recording apparatus by brazing. A conductor wire connection end structure of a substrate, characterized in that, in the end portion of the plurality of conductor wires, a slit located in the widthwise central portion of the conductor wire for accumulating molten brazing during brazing is formed, respectively. Flexible printed circuit board end structure for connection. 3. The flexible printed circuit board connection according to claim 1, wherein each of the slits is formed to have a length substantially equal to a length of a brazed portion of an end portion of the conductive wire. Edge structure. 4. The end structure for connecting a flexible printed circuit board according to claim 3, wherein each of the slits is formed in an open shape at an end of a conductive wire.